1. Field of the Invention
The present invention relates generally to dental implants, and more particularly, but not by way of limitation, to an improved cylindrical dental implant capable of being immediately fixed in a hole formed in bone.
2. Description of Related Art
The use of cylindrical dental implants to anchor dental prostheses in bone is well known. Generally, a hole is drilled in the jawbone of a person and an implant is driven into the hole. After bone has been allowed to heal and regenerate about the implant, the prosthesis is secured to the implant.
To function effectively, it is important that the implant remain securely fixed in the bone. The ability of the implant to remain fixed to the bone is dependent upon the ability of the implant to react as part of the bone, or more specifically, the ability of the bone to adaptively seal about the implant. Because of the rotational and lateral forces that are exerted on implants by activities such as chewing food, the sealing of the bone about the implant alone is often not sufficient to keep the implant permanently fixed in the hole. To this end, various attempts have been made to mechanically enhance the interaction between the bone and the implant.
Several prior art implants have been proposed which employ grooves or flutes along the periphery of the implants. The grooves and flutes are intended to receive new bone growth and thus inhibit rotation and vertical displacement of the implant relative to the bone. While these devices have achieved varying degrees of success, problems have nevertheless been encountered. For example, when drilling the hole in which the implant is disposed, it is often difficult to form a perfectly round hole because of the limited space and the angle from which one must drill, especially when drilling a hole in the back of a patient's mouth. The holes will often end up oval-shaped or significantly oversized. Since cylindrical implants are designed to be press fitted in the hole, a hole that is not precisely dimensioned will not adequately hold the implant during the important initial stages of the healing period. As such, the chances that the implant can be upset during the healing period are increased.
In an attempt to ensure that the implant remains in a fixed position during the healing period, prior art implants have been proposed which employ projecting members that extend from the outer surface of the implant and cut into the bone as the implant is driven into the hole. One such implant is disclosed in U.S. Pat. No. 4,854,873, issued to Linden. The Linden patent discloses a cylindrical implant with a flat proximal end and a rounded distal end. Projecting members are formed on the cylindrical surface in such a manner that the projecting members taper from the proximal end toward the distal end. As the implant is driven into the hole, the projecting members cut a vertical channel in the bone. The implant is then twisted thereby forming undercuts in the bone which function to rigidly lock the implant in position.
U.S. Pat. No. 4,915,628, issued to Linkow et al., discloses an implant having rounded longitudinal columns projecting outwardly from the outer surface of the implant. A curved cutting edge is formed on one end of the columns. During insertion of the implant into a hole, the cutting edges cut slots in the bone. The slots receive the longitudinal columns so as to prevent the implant from rotating within the hole.
As with the implants that employ grooves and flutes, problems have been encountered with use of the prior art implants that employ outwardly extending projecting members, including those taught by the above mentioned patents. In particular, the cutting and crushing of bone, which results from the use of the prior art implants mentioned above, substantially increases the healing period. Cutting and crushing of bone further effects a great deal of trauma to the bone which in turn increases the chances that the bone will fail to hold the implant.
The round designs of dental implants have many inherent weaknesses. Their lack of resistance to rotational forces and of firm immediate fixation are noted by all. An oval or even modified figure "8" design would be better. Why then is virtually every major dental implant in current production round? The answer is that the only uniform, repeatable, predictable receptor site in the bone must be mechanically produced by dental cutting drills. This dictates that a hole must be round and of differing measured lengths, thus the implant must also be round.
While the referenced previous art has attempted to make improvements on the standard cylinder implant, the unique design of the present invention provides the maximum capacity of immediate fixation with the minimum of trauma or displacement of bone.
In view thereof, it can be seen that a need has long existed for an improved cylindrical dental implant that can be immediately fixed in bone, while not excessively traumatizing or damaging the bone. It is to such an improved dental implant that the present invention is directed.